Variable stars are stars that change
their brightness, often with a predictable rise and fall. Beta Lyra
is one of these stars.

The constellation Lyra is
high in the evening skies for most of summer. The bright star Vega
is easy to spot as are the four stars forming a parallelogram below it.
One of these four stars, Beta Lyra, is an eclipsing binary. Every
twelve days the two stars that make up Beta Lyra, complete an orbit around
one another, as the larger, darker star passes in front of it's brighter
companion we, on earth, notice the star getting dimmer. This is a slow
and difficult process to measure.

Using our Astrovid Video camera
we captured images of Beta Lyra and, for reference, Vega.
The image below shows four images of Beta Lyra (on left) beside an image
of Vega (on right) The images were captured on four different nights.

Using a computer we "zoomed" in
on these images until we could see the individual pixels that made up the
star images. These pictures are a measure of the brightness of these stars.

(Click on the image if you would
like to download it and zoom in yourself. You will need a graphics program
like Corel Photopaint or Lview to be able to zoom on the image.)

The reason we captured an image
of Vega, which does not change in brightness, was so that we could
compare the transparency of the atmosphere each night to be sure that Beta
Lyra did not look dimmer because some thin clouds had moved in.

To accurately measure the brightness
of Beta Lyra we created a computer program to calculate the ratio
of the brightness of Beta Lyra to Vega . This method allows
for any variation caused by the atmosphere.

If you would like a copy of the
program, starlite.exe, with instructions and
images to work with click here: starlite